An ad hoc network communication technology refers to a communication technology in which each apparatus performs a direct communication without any access points between the apparatus. In recent years, a wireless ad hoc network technology has been attracting attention in which each communication apparatus to which the ad hoc communication technology is applied recognizes peripheral communication apparatus.
An example of a routing protocol of an ad hoc network (an ad hoc protocol) may include a reactive type AODV (an Adhoc On Demand Distance Vector Algorithm) or a proactive type OLSR (an Optimized Link State Routing). An example of the proactive type routing protocol includes a protocol that constructs a route for which each of the nodes autonomously performs a data communication prior to a communication request, learns an optimal route as needed, and changes the route.
The OLSR employs a scheme which grasps an entire network and detects the route to a target communication node, as each of the communication node apparatuses exchanges frames on a regular basis. Each of the communication node apparatuses sends out a HELLO frame cyclically and reports its existence with the others. When the existence of the communication node apparatus that becomes a communication partner is found, next, a path for flooding is generated to efficiently distribute a frame to the entire network. This is called an MPR (Multi Point Relay).
With the MPR, a frame may be efficiently broadcast from each of communication node apparatuses to the entire network. Next, as each of node apparatuses distributes to the others a TC (Topology Control) frame that is a route creation message by using the MPR, all of the node apparatus may know a network topology.
In sending a frame to a target communication node apparatus, the communication node apparatus that becomes a sending source refers to a network topology that the communication node apparatus knows and entrusts a frame to an adjacent communication node apparatus that is to be sent. The adjacent node apparatus performs similar processing and a frame is eventually delivered to the target node apparatus.
Examples of technologies with regard to the ad hoc network include the following technologies.
The first technology is directed to a method for participating in a wireless network of a wireless terminal that performs a wireless network communication with a service provider through a plurality of relay devices (for example, Patent Document 1). According to the first technology, in performing a wireless network communication, a wireless terminal accesses a specified relay device and transmits its own address. The relay device that has received the address of the wireless terminal by this transmission reports the address to the other adjacent relay device and establishes a communication route between the wireless terminal and the service provider.
Further, there is the second technology of suppressing a communication between a Kernel space and a user space that is generated at the time of packet transfer processing (for example, Patent Document 2). According to the second technology, a mobile communication apparatus includes a route table that has route information. When receiving a packet from a node N1 addressed to a node N2, a route decision unit within the Kernel space decides whether or not there is route information addressed to a node N2 in the route table. When there is route information, the Kernel space transmits a packet to a node N2. When there is no route information, the Kernel space requests that the user space explore route information. The Kernel space 20 transmits the packet to the node N2 after it has received the explored route information. With the operations mentioned above, a communication occurs between the Kernel space and the user space only when there is no route information within the route table RT.
Further, there is the third technology in which even though each of node apparatuses does not recognize a network topology at the time when data is transmitted, as a result of autonomous distribution processing by each of the node apparatuses, as an entire network, an appropriate route is selected and data is transmitted (for example, Patent Document 3). In the third technology, when the frame that has been transmitted by the above mentioned node apparatus is received by the above mentioned node apparatus through a network, an adjacent node apparatus that differs from the adjacent node apparatus that was selected previously is tested as a transmission destination. And when there is no transmittable adjacent node apparatus, a reception frame is transmitted to the third adjacent node apparatus by a backtracking means, and accordingly, another new route may be tested by the third adjacent node apparatus.    Patent Document 1: Japanese Laid-open Patent Publication No. 2006-129381    Patent Document 2: Japanese Laid-open Patent Publication No. 2005-260299    Patent Document 3: International Patent Application Publication No. 2011/013165